This article,
reporting on a new spokesperson contract signed,
starts out:

Microsoft Corp., weary of being cast as a
stodgy oldster by Apple Inc.'s advertising, is turning
for help to Jerry Seinfeld.

Hello?
Jerry Seinfeld is 54 years old!
He's actually older than Bill Gates himself.
Now I don't want to say 54 is very old,
but it's certainly not young.
John Hodgman, who plays "a PC" in Apple's advertising,
is only 37 years old.
(37 is my own age.
Hodgman is actually about three months younger than I am.)
That may not be young either,
but Jerry Seinfeld is old enough to be Hodgman's father
(physically, speaking, anyway).
Hodgman's counterpart in Apple's advertising, Justin Long,
is 30 years old. Thirty is widely regarded as the
"starting to get old" age for most people.
At least he's not young enough to be Hodgman's kid.

To give you an idea of how a 54 year old fits into
the worldview of a 37 year old, when Wilford Brimley was
doing Quaker Oats commercials in 1988,
he was 54. Brimley had just finished up working on a
TV show where he played a grandfather.
A grandfatherly man will not help Microsoft
win over the youth market.